In image reproduction devices having the capability of varying the image ratio of the image produced, it is desirable to be able to control the size of the image-free zones, such as the margins. For example, copying apparatus have been developed in which the width of a binding margin can be controlled, U.S. Pat. Nos. 4,501,490 and 3,967,896 or where the size of the original is smaller than the transfer means, charge quenching has been used to maintain a clean margin. U.S. Pat. No. 4,384,785. Additionally, various charge quenching devices are used to eliminate unnecessary charges on the non-imaged area of a photoconductor, e.g., British application G.B. No. 2012073A.
In U.S. Pat. No. 3,967,896, which describes a copying device in which it is possible to make copies whose image-free edge zones on the left and right of the copy (side margins) are sufficiently wide for fastening or binding edge at the left-hand side by charging these image-free zones. However, in so doing there is a loss of information-which results from changing the width of image-free edge zones. This loss can be obviated by reproducing the image of the original in a somewhat reduced scale on the copy. The correct adjustments of the copying device must be manually determined by the operator by making one or more sample copies.
U.S. Pat. Nos. 4,162,844 and 4,187,024 describe similar copying devices suitable for making double-sided copies (duplex copies) and having adjustment facilities to make the image-free edge zones on the front and the reverse sides of the copy to coincide. As with the device described above these require the operator to determine the correct adjustments by making sample copies.
The need to make sample copies is a distinct disadvantage of the prior art devices. This is particularly the case when a reduction in the size of the image appears to be necessary to avoid loss of information on the copies. In such a case determination of the correct machine adjustments can be very time-consuming. Accordingly, it is an object of the present invention to provide a reproduction device in which it is possible to supply to the control means data concerning the width of each of two oppositely situated image-free edge zones of an original to be reproduced together with the required minimum width of the corresponding edge zones on the sheet of receiving material to calculate the image ratio and activation time of the process controls. It is a further object of the invention to provide control means which utilize the data supplied for calculating the imaging ratio and an adjustment or an activation time of at least one of the process functions in order to obtain the required minimum width of the edge zones and also generating control signals to control the relevant process functions in accordance with the calculated values; thus overcoming the limitations inherent in prior art devices.